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    <title>Document</title>
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<body>

    <script>

        var arr = [1,2,3] ;

        var arr = ['a' , 'b' , 'c'] ;

        // 二维数组
        var arr = [
            [1,2,3] , 
            [4,5,6] ,
            [7,8,9]
        ] ;

        console.log(arr[0]) ;     // [1,2,3] 
        console.log(arr[0][0]) ;  // 1

        console.log(arr[2][1]) ;



        // 二维数组的遍历
        for(var i = 0 ; i < arr.length ; i++) {
            for(var j = 0 ; j < arr[i].length ; j++) {
                console.log(arr[i][j]) ;
            }
        }

    </script>
    
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